1. Field of the Invention
The present invention relates to a mobile terminal device provided with a plurality of keys to each of which a plurality of functions are assigned, and to a program used in this mobile terminal device.
2. Description of the Related Art
As a mobile terminal device such as a mobile telephone or a personal digital assistant (PDA), a mobile terminal device, which is provided with function keys for calling functions installed therein, has heretofore been widely known. Moreover, a mobile terminal device, in which a plurality of functions are assigned to a single function key, has also been known. This is because it is preferable that a mobile terminal device not be provided with a large number of function keys when portability of the mobile terminal device is focused.
In such a mobile terminal device, for example, a key is assigned to a function for inputting a character corresponding to that assigned to the key in a case where the key is pressed for a period of time shorter than a predetermined judging time (in the case of a “normal press”). The key is assigned to a function for calling an edit screen for a mail in a case where the key is pressed for a period of time longer than the predetermined judging time (in the case of a “longer press”) (see Japanese Patent Application Laid-open No. 2003-60741, for example).
In addition, there is also known a mobile terminal device in which a function to call an address book, a function to call a screen for changing a ring tone, a function to start a game, a function to call a screen for editing a schedule, and so forth are assigned to the respective keys (see Japanese Patent Application Laid-open No. 2003-298716, for example).
Meanwhile, there is also known a mobile terminal device in which an explanation (a preview) on a function to be executed is displayed in a display area when a key is pressed, in order to enhance user-friendliness.
Specifically, such a mobile terminal device detects key touch by a user in addition to key press by the user, and displays the explanation on the function in the display area at the time of detecting the key touch (see Japanese Patent Application Laid-open No. 2003-149308, for example).
However, the mobile terminal device is generally provided with small keys since the portability of the mobile terminal device is important.
Hence, in the mobile terminal device configured to execute different functions respectively in response to the “normal press” and the “long press” on a certain key, it is difficult to print explanations on the functions respectively corresponding to the “normal press” and the “long press” on the key. For example, in a case where the explanation on the function corresponding to the “normal press” is printed on the key and the explanation on the function corresponding to the “long press” is not printed thereon, a user has to memorize the function corresponding to the “long press” on the key.
On the other hand, in the mobile terminal device configured to display the explanation on the function in the display area at the time of detecting the key touch by the user, it is assumed that only one function (the function corresponding to the “normal press”) is assigned to each of the keys. Specifically, in such a mobile terminal device, displaying of the explanation on the function is triggered by the key touch. Accordingly, even when the plurality of functions are assigned to one key, it is difficult to cause the user to notice that the explanation displayed in the display area represents the explanation on the function corresponding to the “long press”.